This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. COGNITION in New World Primates This project has the goal of developing cognitive tasks for use with New World primates, common marmosets (Callithrix jacchus) and cotton-top tamarins (Saguinus oedipus). During the past year we continued our work on a form of cognition termed implicit learning. In humans, implicit learning refers to improvements in performance on a task without the concomitant ability of the subject to verbalize what has been learned. In our application of this paradigm to tamarins, we define implicit learning as learning that occurs in the absence of reinforcement for that learning. Many of our tasks involve exposing tamarins to patterned information such as a series of stimuli presented sequentially, with reinforcement delivered randomly, independent of performance. We later test the tamarins to assess what they learned about the pattern. In humans, this type of learning has been characterized as of ancient origin, and, hence, unconnected to language. Implicit learning is also of interest given that it is conserved in disorders such as amnesia, whereas other forms of learning are degraded. Conversely, it is severely impaired in motor-related disorders such as Parkinson's disease, although other types of learning are conserved.